1. Field of the Invention
The present invention relates to a method for detecting abnormality of a current sensor in a battery pack, and more particularly, to a method and an apparatus for detecting abnormality of a current sensor in a battery pack by measuring voltage and current flowing in the battery pack.
2. Description of the Related Art
As the demands for portable electronic products such as notebooks, video cameras and cellular phones are rapidly increased in these days, and development of electric vehicles, energy storage batteries, robots, satellites, etc. is under active progress, numerous studies are being made on high-performance secondary batteries capable of being repeatedly charged and discharged.
Currently, nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries or the like are commercially available as secondary batteries. Among them, lithium secondary batteries are the center of interest because they hardly have memory effects and can be freely charged or discharged when compared with nickel-based secondary batteries. Advantageously, lithium secondary batteries also exhibit very low self-discharge and high energy density.
In a battery pack including such secondary batteries, a power supply system generally has a current sensor for measuring electric current. The current sensor monitors the state of a battery pack by measuring electric current flowing in the battery pack, and senses over-current that may flow in the battery pack. If the current sensor is beyond normal operation due to malfunction or the like, it is impossible to exactly measure electric current flowing in the battery pack. As a result, when abnormality occurs such as over-current or the like, if it is not properly handled, severe problems may take place, for example, explosion of the battery pack and so on.
To solve the problems, some conventional current sensors are provided with a detection function for detecting whether or not abnormality exists in the current sensors, however this function does not guarantee a perfect operation but has the likelihood of malfunction. Unlike a voltage sensor, a current sensor is applied by various measurement and output methods, and for this reason, it needs to develop corresponding software modules depending on types of current sensors so as to properly realize a function for detecting abnormality of a current sensor. However, it disadvantageously takes much development costs and time.